HJ 668-2013 English PDFUS$319.00 · In stock
Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email. HJ 668-2013: Water quality. Determination of total nitrogen by flow injection analysis(FIA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry Status: Valid
Basic dataStandard ID: HJ 668-2013 (HJ668-2013)Description (Translated English): Water quality. Determination of total nitrogen by flow injection analysis(FIA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry Sector / Industry: Environmental Protection Industry Standard Classification of Chinese Standard: Z16 Classification of International Standard: 13.060 Word Count Estimation: 12,181 Quoted Standard: HJ/T 91; HJ/T 164 Regulation (derived from): Ministry of Environmental Protection Notice No. 63 of 2013 Issuing agency(ies): Ministry of Ecology and Environment Summary: This standard specifies the determination of total nitrogen in water flow injection - Hydrochloride naphthylethylenediamine spectrophotometry. This standard applies to surface water, groundwater measurement, sewage and industrial effluent total nitrogen. HJ 668-2013: Water quality. Determination of total nitrogen by flow injection analysis(FIA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order. Water quality.Determination of total nitrogen by flow injection analysis (FIA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry National Environmental Protection Standard of the People's Republic Determination of total nitrogen in water Flow injection-naphthylethylenediamine hydrochloride spectrophotometry Water quality-Determination of total nitrogen by flow injection analysis (FIA) and N-(1-naphthyl)ethylene diamine dihydrochloride Published on.2013-10-25 2014-01-01 Implementation release Ministry of Environmental Protection ContentForeword. II 1 Scope.1 2 Normative references.1 3 principle of the method.1 4 Interference and elimination 1 5 Reagents and materials 2 6 Instruments and equipment 3 7 sample 3 8 Analysis steps.3 9 Calculation and representation of results. 4 10 precision and accuracy. 4 11 Quality Assurance and Quality Control..5 12 Notes.6 Appendix A (informative) Persulfate purification method.7ForewordTo implement the Environmental Protection Law of the People's Republic of China and the Law of the People's Republic of China on Water Pollution Prevention and Control, to protect the environment, To ensure human health, standardize the determination method of total nitrogen in water, and develop this standard. This standard specifies the flow injection-naphthylethylenediamine spectrophotometric method for the determination of total nitrogen in water. This standard is the first release. Appendix A of this standard is an informative annex. This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection. This standard is mainly drafted by. Suzhou Environmental Monitoring Center Station and Changshu Environmental Monitoring Station. The standard verification unit. Beijing Environmental Protection Monitoring Center, Nantong Environmental Monitoring Center Station, Jiangsu Marine Fisheries Research Research Institute, Water Quality Testing Center of Suzhou Water Supply Company, Zhenjiang Environmental Monitoring Center Station and Changshu Environmental Monitoring Station. This standard was approved by the Ministry of Environmental Protection on October 25,.2013. This standard has been implemented since January 1,.2014. This standard is explained by the Ministry of Environmental Protection. Determination of total nitrogen in water - Flow injection - Naphthylethylenediamine hydrochloride spectrophotometric method1 Scope of applicationThis standard specifies the flow injection-naphthylethylenediamine spectrophotometric method for the determination of total nitrogen in water. This standard applies to the determination of total nitrogen in surface water, groundwater, domestic sewage and industrial wastewater. When the detection optical path is 10mm, the detection limit of this method is 0.03mg/L (in N), the measurement range is 0.12 mg/L ~10mg/L.2 Normative referencesThe contents of this standard refer to the terms in the following documents. For undated references, the valid version applies to this standard. quasi. HJ/T 91 Surface Water and Wastewater Monitoring Technical Specifications HJ/T 164 Technical Specifications for Groundwater Environmental Monitoring3 Principle of the method3.1 Working principle of flow injection analyzer In a closed pipeline, a volume of the sample is injected into the continuous flow of the carrier liquid, and the sample and reagent are in the chemical reaction module. Mix and react in the specified order and proportion. Under the condition of incomplete reaction, enter the flow detection cell for photometric detection. 3.2 Method of chemical reaction principle In an alkaline medium, the nitrogen-containing compound in the sample is oxidized to a nitrate by persulfate at 95 ° C ± 2 ° C under ultraviolet irradiation. After the acid salt, it is reduced to nitrite by cadmium column; in acidic medium, nitrite and sulfonamide are diazotized, and then with salt The acid naphthyl ethylenediamine was coupled to form a purple-red compound, and the absorbance was measured at 540 nm. Refer to the work flow chart, as shown in Figure 1. 1 peristaltic pump 2 heating tank (95 ° C) 3 UV digestion device 4 bubble removal device 5 Injection valve 6 Reaction ring 7 Cadmium column 8 Detection cell 10mm 540nm R1 digestion solution (5.16) R2 sodium tetraborate buffer solution (5.17) R3 ammonium chloride buffer solution (5.18) R4 developer (5.19) C carrier liquid (5.27) S sample W waste liquid Figure 1 Flow injection-naphthylethylenediamine hydrochloride spectrophotometric determination of total nitrogen reference work flow chart4 interference and elimination4.1 When the sample contains a high concentration of organic matter, it will consume potassium persulfate oxidant, so that the determination result of total nitrogen is low. The sample is over-diluted to eliminate the effect, but it needs to be confirmed by the consistency of the multiple dilution ratio determination results or the spike recovery experiment. 4.2 When the concentration of copper ions, iron ions, hexavalent chromium ions and chloride ions in the sample are not more than 100mg/L, 250mg/L, 100 respectively At mg/L and 10000 mg/L, there was no effect on the determination of total nitrogen.5 reagents and materialsAnalytical purification reagents that meet national standards were used for analysis unless otherwise stated. Experimental water is freshly prepared and charged Ammonia-free water with a resistivity greater than 10 MΩ·cm (25 ° C). In addition to the standard solution, other solutions and experimental water are used with helium (5.28) Or ultrasonic degassing. 5.2 Hydrochloric acid. ρ (HCl) = 1.18 g/ml. 5.3 Phosphoric acid. ρ(H3PO4) = 1.69 g/ml. 5.4 Sulfuric acid. ρ(H2SO4) = 1.84 g/ml. 5.5 sodium hydroxide (NaOH). 5.6 potassium persulfate (K2S2O8). 5.7 Sodium tetraborate decahydrate (Na2B4O7·10H2O). 5.8 Ammonium chloride (NH4Cl). 5.9 Disodium edetate dihydrate (Na2EDTA·2H2O). 5.10 Sulfonamide (C6H8N2O2S). 5.11 Naphthylethylenediamine hydrochloride (C12H16Cl2N2). 5.12 Potassium nitrate (KNO3). excellent grade, dried at 105 ± 5 ° C °C and stored in a desiccator. 5.13 Potassium nitrite (KNO2). 5.14 Glycine (glycine, H2NCH2COOH). Store in a cool place. 5.15 sodium hydroxide solution. c (NaOH) = 15mol/L 600 g of sodium hydroxide (5.4) was weighed and dissolved in water and diluted to 1 L with water. 5.16 Digestion solution. Weigh 49.0g of potassium persulfate (5.6) dissolved in 900ml of water, then add 10.0g of sodium tetraborate decahydrate (5.7), with water Dilute to 1000ml and mix. The solution is stored at room temperature and is stable for 1 month. 5.17 sodium tetraborate buffer solution (pH=9.0) Weigh 25.0g of sodium tetraborate decahydrate (5.7) dissolved in 900ml of water, adjust the solution with sodium hydroxide solution (5.15) Mix to pH 9.0, dilute to 1000 ml with water, and mix. The solution is stored at room temperature and is stable for 1 month. 5.18 Ammonium chloride buffer solution (pH=8.5) Weigh 85.0g ammonium chloride (5.8) and 1.0g disodium edetate dihydrate (5.9) dissolved in 800ml of water, with water Dilute to 1000ml and mix. Adjust the pH of the solution to 8.5 with sodium hydroxide solution (5.15). The solution is stored at 4 ° C. It can be stable for 1 month. 5.19 chromogenic agent Measure 100 ml of phosphoric acid (5.3) dissolved in 600 ml of water, add 40.0 g of sulfonamide (5.10) and 1.0 g of naphthylethylenediamine hydrochloride (5.11), dilute to 1000 ml with water, mix well, and store in a brown bottle. The solution was stored at 4 ° C and was stable for 1 month. However, if the color of the solution turns pink, it should be stopped immediately. 5.20 Potassium nitrate standard stock solution. ρ(N)=1000mg/L Weigh 7.218g potassium nitrate (5.12) dissolved in water, transfer to a 1000ml volumetric flask, dilute with water and mix well. Reagent bottle. The solution is stored in the dark at 4 ° C for at least 6 months. 5.21 Potassium nitrate standard intermediate solution. ρ(N)=100mg/L Measure 10.00 ml of potassium nitrate standard stock solution (5.20) in a 100 ml volumetric flask, dilute to volume with water, and mix in reagent bottle. The solution was stored in the dark at 4 ° C and was stable for 1 month. 5.22 Standard use solution of potassium nitrate. ρ(N)=10.0mg/L Accurately measure 10.00ml of potassium nitrate standard solution (5.21) in a 100ml volumetric flask, dilute with water and mix well. Bottle. The solution was stored at 4 ° C in the dark and stable for 7 days. 5.23 Glycine standard stock solution. ρ(N)=1000mg/L Weigh 5.360g of glycine (5.14) dissolved in water, transfer to a 1000ml volumetric flask, dilute to volume with water and mix well. In the reagent bottle. The solution was stored at 4 ° C in the dark and stable for 3 months. 5.24 Glycine standard use solution. ρ (N) = 10.0 mg/L Accurately measure 10.00ml of aminoacetic acid standard stock solution (5.23) in a 1000ml volumetric flask, dilute to volume with water and mix. Available at the time of use. 5.25 potassium nitrite standard stock solution. ρ (N) = 1000mg/L Weigh 6.079g of potassium nitrite (5.13) dissolved in water, transfer to a 1000ml volumetric flask, dilute to volume with water and mix well. In a brown bottle. The solution is stored in a sealed container at 4 ° C for at least 1 month. 5.26 Standard use solution of potassium nitrite. ρ(N)=10.0mg/L Accurately measure 10.0ml of potassium nitrite standard stock solution (5.25) in a 1000ml volumetric flask, dilute to volume with water and mix. Available at the time of use. 5.27 Carrier liquid. no ammonia. 5.28 Helium. Purity ≥99.99%.6 Instruments and equipment6.1 Flow Injection Analyzer. Autosampler, chemical reaction unit (ie analysis module, channel, peristaltic pump, injection valve, Reaction line, UV digestion device, cadmium column and other components), detection unit (circulation detection pool optical path is 10mm) and data Processing unit. 6.2 Balance. The accuracy is 0.0001g. 6.3 pH meter. accuracy is 0.02. 6.4 Ultrasonic machine. frequency 40KHz. 6.5 Common instruments and equipment used in general laboratories.7 samplesSamples were collected and stored in accordance with the relevant regulations of HJ/T 91 and HJ/T 164. Wash all containers that contact the sample with water before sampling. Collect samples in polyethylene or glass bottles with sulfuric acid (5.4) Acidified to pH ≤ 2, can be stored for 7d at room temperature. Or collected in a polyethylene bottle, frozen at -20 ° C, can be stored for 1 month.8 Analysis steps8.1 Commissioning of the instrument Install the analysis system, set the operating parameters, and operate the instrument according to the instrument manual. After starting the machine, first replace the reagent with water, check The integrity of the flow path and the smoothness of the liquid flow are analyzed. After the baseline is stabilized (about 20 min), the system starts to enter the reagent. After the baseline is stabilized again, proceed to 8.2~8.4. 8.2 Calibration 8.2.1 Preparation of the standard series Transfer the appropriate amount of potassium nitrate standard solution (5.21) separately, dilute to 100 ml with water, and prepare the standard of 6 concentration points. Quasi-series. Total nitrogen concentrations were. 0.00 mg/L, 0.15 mg/L, 1.00 mg/L, 2.00 mg/L, 5.00 mg/L and 10.0 mg/L. 8.2.2 Drawing of the calibration curve Take appropriate amount of standard series solution (8.2.1), placed in the sample cup, respectively, from the low concentration to high concentration by the injector Sampling and measurement. Taking the measured signal value (peak area) as the ordinate, the corresponding total nitrogen mass concentration (in N, mg/L) For the abscissa, draw a calibration curve. 8.3 Determination The measurement of the sample was carried out under the same conditions as in the drawing of the calibration curve. Note. If the total nitrogen content of the sample exceeds the calibration curve detection range, the appropriate amount of sample should be diluted and measured on the machine. 8.4 Blank test Take an appropriate amount of experimental water instead of the sample and perform a blank test in accordance with step 8.3.9 Calculation and representation of results9.1 Calculation of results The mass concentration of total nitrogen (in N, mg/L) in the sample was calculated according to formula (1). Yaf ρ −= × (1) In the formula. Ρ--the mass concentration of total nitrogen in the sample, mg/L; Y--determine the signal value (peak height); a -- the intercept of the calibration curve equation; B--the slope of the calibration curve equation; F--dilution factor. 9.2 Results representation When the measurement result is less than 1.00 mg/L, the result is retained to two decimal places, and the result is 1.00 mg/L or more. Leave three valid numbers. 10 Precision and accuracy 10.1 Precision Six laboratories tested uniform samples with total nitrogen concentrations of 0.10 mg/L, 1.22 mg/L, and 2.99 mg/L. The relative standard deviations in the room were 1.0%~9.1%, 0.6%~6.1% and 0.6%~6.7%, respectively; the relative standard deviation between laboratories 3.3%, 2.4%, 1.7%, respectively; repeatability limits were. 0.02 mg/L, 0.07 mg/L, 0.08 mg/L; reproducibility limits Do not. 0.03mg/L, 0.10mg/L, 0.16mg/L. 10.2 Accuracy 6 laboratories were labeled with total nitrogen concentrations of 0.50±0.06mg/L, 1.22±0.09mg/L, and 2.99±0.016 mg/L, respectively. Quasi-solution determination. relative error. 0.4%~8.3%, 0.0%~5.7%, 0.3%~3.0%; relative error final value They were. 3.6% ± 5.8%, 1.4% ± 4.4%, and 1.3% ± 2.4%. The total nitrogen concentration in the six laboratories was 0.25 mg/L to 2.94 mg/L, 0.53 mg/L to 3.58 mg/L, and 0.67 mg/L to 5.34, respectively. The three actual samples of mg/L were spiked and recovered. The recoveries were 98.0%~108% and 92.0%~103%, respectively. 90.0%~108%; the final values of the spiked recovery were. 103%±7.2%, 97.9%±8.0%, 96.6%±14.3%. 11 Quality Assurance and Quality Control 11.1 Blank test At least 2 blanks shall be made for each batch of samples, and the blank value shall not exceed the method detection limit. Otherwise, the cause should be identified and reanalyzed The sample can not be determined until it is qualified. 11.2 Calibration validity check A calibration curve must be drawn for each batch of samples. The correlation coefficient of the calibration curve is γ ≥ 0.995. For each sample analyzed, a calibration curve intermediate concentration solution is used for calibration verification, and the measurement results are relatively biased. The difference should be ≤ 5%, otherwise the calibration curve should be redrawn. 11.3 Precision Control At least 10% of the parallel samples should be determined for each batch of samples. When the number of samples is less than 10, at least one parallel sample should be determined. When the total nitrogen concentration of the sample is ≤1.00mg/L, the allowable relative deviation of the parallel sample should be ≤10%; when the total nitrogen concentration is >1.00mg/L, The allowable relative deviation of parallel samples should be ≤ 5%. 11.4 Accuracy Control At least 10% of the spiked samples shall be determined for each batch of samples. When the number of samples is less than 10, at least one spiked sample shall be determined. Product, the standard recovery rate should be between 80~120%. If necessary, each batch of samples shall have at least one QC sample of known concentration, and the test results shall be within the range of uncertainty given by it. Inside. 11.5 System Performance Check 11.5.1 UV digestion efficiency test The standard use solution of aminoacetic acid (5.24) was periodically measured to verify the digestion efficiency of the method. It is usually checked once every 3 months. First calibrate the system (8.2), then parallel determination of the standard use solution of aminoacetic acid (5.24) and standard solution of potassium nitrate (5.22). Calculate the digestion efficiency R by the formula (2), and R should be greater than 90%. 100%R ρρ= × (2) In the formula. R--digestion efficiency, %; Ρ1--aminoacetic acid standard use solution (5.24) determination results, mg/L; Ρ2--potassium nitrate standard use solution (5.22), mg/L. 11.5.2 Inspection of cadmium column reduction ability When the color of the cadmium column is found to be silvery gray or white precipitate, the cadmium column reduction ability test is required. Turn off purple in the test The external lamp is replaced by water instead of the digestion solution (5.16). According to the same procedure as the sample determination, measure the same nitrous content with the same nitrogen content. Potassium acid solution (5.26) and potassium nitrate standard use solution (5.22). If the latter measurement result is 10% lower than the former, then The cadmium column needs to be replaced. It is usually checked once a month. Note. When the measured result of the certified reference material is lower than the lower limit of its uncertainty range, 11.5 is required. 12 Precautions 12.1 Because the flow path of the flow injection analyzer is small, it is not suitable for determining more particulate matter or larger particle size than suspended particles. 250 μm sample. 12.2 Reagent and ambient temperature influence analysis results, the reagents stored in the refrigerator should be placed at room temperature (20 ± 5 ° C) before use. During the analysis, the room temperature is preferably kept above 20 °C to prevent the digestion solution (5.16) solute from clogging the pipeline, and the temperature fluctuates. Can not exceed ± 2 ° C. 12.3 When preparing the digestion solution (5.16) and sodium tetraborate buffer solution (5.17), the heating and dissolution temperature must be controlled at 60 ° C. under. 12.4 To reduce baseline noise, the reagents should be kept clear and filtered if necessary. Closed chemical reaction system will dry if there are bubbles Disturbance measurement, therefore, all solutions except the standard solution must be degassed, degassing with helium for 1 min or ultrasonic degassing for 30 min. 12.5 The quality of the reagent will affect the blank value. When the blank value exceeds the detection limit, the calibration curve has a low concentration point (0.15mg/L). When the control limit is greater than 10%, the potassium persulfate needs to be purified. See Appendix A for the purification method. 12.6 After each analysis, the analytical pipeline should be cleaned with pure water and the filter in the flow detection tank should be removed in time. Put it into the dryer, it is dustproof and moisture proof. 12.7 Different types of flow analyzers can be selected with reference to this standard to select the appropriate instrument conditions.Appendix A(informative appendix) Persulfate purification method A.1 Reagents and equipment A.1.1 Potassium persulfate. A.1.2 Filter paper or sand core funnel (G2). A.1.3 Beaker. A.1.4 Dryer. A.2 Operation steps Weigh 100 g of potassium persulfate (A.1.1) into a beaker and dissolve it with 500 ml of ammonia-free water at 70 ° C to 80 ° C. Solution natural After cooling ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of HJ 668-2013_English be delivered?Answer: Upon your order, we will start to translate HJ 668-2013_English as soon as possible, and keep you informed of the progress. The lead time is typically 1 ~ 3 working days. 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